Tachometer and odometer.



N. M. HOPKINS.

TAGHOMETER AND ODGMETBR.

APPLIGATION IILBD MAR. 24, 1909 949,746. Patented Feb. 15, 1910.

2 8KEETSSHEBT 1.

135 41. 'uminwmu 1* N. M. HOPKINS. TAUHOMETEB AND ODOHETBB. APPLIOATIOH rum) MAR. 24,1909

949,746. Paf ented Feb.15,1910.

2 SHEETS-SHEET B.

UNITED s'rirrns PATENT ()FFICF.

NEVIL MONROE HOPKINS, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOB TO THE ELECTRIC- SPEEDOME'IER AND DY OF WASHINGTON, DISTRICT OF COLUMBIA.

NAMDMETER MANUFACTURING COMPANY,

A CORPORATION OF DELAWARE.

TACHOMETER AND ODOMETER.

Specification of Letters Patent.

Patented Feb. 15, 1910.

Application filed March T34, 1908. Serial No, 485,470.

To all 2111mm it may concern;

I Be it known that I, Nisvio Moxnon Horitms, a citizen of the United States. residing 1 at \Vashington, in the District of Columbia, have invented certain new and useful improvements in 'lachrm'u-rrers and Odometers, of which the following is a specification.

This invention relates to an electric tachometer and odometer especially designed for use on automobiles, comprising .a directcurrent magneto driven by gears from one of the autoimihile whecls,a milli-voltieter connected with the magneto and having a scale calibrated to indicate speed in distancennits per time-unit, and an odometer driven by the shaft which drives the magneto.

The inventionr-eomprises certain improvements which are hereinafter described and specifically claimed.

Referring to the accompanying drawingz l igure l. is a rear elevation showing the magneto carried by the steering'knucltle of an automobile and connected to speed ind distance meters mounted on the dash boar Fig. 2 is sectional side elevation of the magneto, with its cover removed; Fig. 3 is a longitudinal vertical section of the magneto cover, carr ing an odometer; Fig. 4 is a sectional elevation of the magneto on a plane normalto its shafts, looking toward its magnet; and Fig. is a similar sectional elevation of the magneto, looking in the opposite direction.

The mechanisn'i of the magneto, which is constructed to deliver direct currents, is carried by a horizontal base-plate l and vertical end-plates 2, 3, integral with the base. An integral a perturcd lug: 4. extends down Ward from the base, receiving the arm of a bent standard 5 which supports mags note on one of the stecringknuckles of an ant omobilc. neto is incloscd by a removable cover 6 having a curved top '7. Rectangular ver. tical open slots 8 are cut in the ends of the cover, leaving marginal flanges 9 which enter and make a substantial waterand dust-proof joint with grooves 10 in the side The mechanism of the mag,

alined holes 13, 13' in the cover and baseplate.

\ 14 are secured on the base-plate 1, receiving l screws 15 which pass through this plate into them. The polar extremities of the magnet are bent into arcs 16, to provide a magnetic field within which rotates the armature 17, 5 here shown as tri-polar. It'is desirable i that the armature should have more than two poles in order that the commutator speed may be fairly low, it being impossible to effectively eommutate current when the speed of the eonnnutator-segments relative to the brushes exceeds a certain figure, say one mile per minute, especially with currents of low potential. The armature is carried by a shaft 18, one end of which is journaled in a hole 19 drilled into but not through the end-plate 2, while the other end is journaled in a hole 20 drilled into but not through a plug 21 which is threaded into an opening22 in the'other end-plate 3. The commutator comprises a spool 23 of insulating material, 0. f]. vulcanitc, driven onto the shaft 18, and three strips 2t of an inoxidizable fairly hard metal or alloy, 6. g. platinum or platinum-iridium. the ends 25 of which are bent outward-at right angles to lie against the ends of the spool 23 and are riveted thereto. The three leads from the armature windings are soldered to one end of these strips. The brushes'QG consist preferably softer'than that of the strips 24, .c. (1. gold, so thatthe wear due to frictlon will largely be onthe brushes, which. are easily renewed. Each brush is carried by a spring-wire 27, which is bent and hun on a horizontal support 28. The free en each wire is bent into a hook 29, receiving an eye at one end of a coiled tension-spring 30, the other end of which is soldered to a horizontal metal strip 31 carried byan insulating strip which is riveted to the baseplate 1. To the strips 31 are respectively E secured the two wires of a cable 33 which St; The brush-supports 28 are metal rods, secured at one end in the insulating bushings fixed in a metal bar 36 which is clamped against the outer face of the magnet 14 by a scr'eWBT threaded into the ver- The ends of a vertical horseshoe magnet of an inoxidizable metal or alloy which is delivers electric current to the speed meter" of the internal tutor-shaft of themagneto, The

tical plate2. This bar not only carries the brushes, but clamps the magnet firmly against the end-plate 2. Each sup ort 28 has annular grooves 38 to receive t e bent portions of the brush-wires 27.

The armature is driven by a ear 39 pinned onto the shaft 18 which mes es with a smaller r40 pinned on an upper shaft 41-, the en. of which pass through and are journaled in openings m the vertical'plates 2, 3. One end of shaft '41 receives a pinion 42 which meshes with a gear 43 fixed on the automobile wheel. Theother end of the shaft 41 passes throu ha threaded boss 44 on the outer side of p ate 3, which mayireceive a cap 45; By interposing the reduction gears. 39, 40 between the commutatorshaft 18 andthe driving-shaft 41, the speed of the commutator-segments relative to the brushes may be reduced to a figure which enables the weal: low-tension currents generated by this magneto to be successfully commutated, emp oying' segments and brushes of noxidlzable precious metals or alloys. The teeth of the gears 43, 42 which transmit powerfrom the vehicle-wheel .to thedriving-shaft- 41 are necessarily coarse or of large pitch, and the teeth of the gear 48 strike intermittent heavy -or hammerlike blows on the teeth of the gear 42, so that it is impracticable to directl employ. the shaft 41 as the armatures an commugears 40, 39 'connecting the driving-shaft 41 and the magneto-shaft are, however, comparatively fine, or of small pitch relative to those of the external gears, so that the armatureshaft is given a smooth and uniform rota tion without vibration or chattering. B reason of the relative fineness of the teet (gears, it is necessary that these gears shoul be protected from the dust and grit of the road, that is, that they should be inclosed in the substantially waterand dust-proof case.

By removing the cap 45, the shaft 41 may be coupled by a in 46 to a flexible shaft 47 leading to an o ometer 48 mounted on the dash-board of the automobile. The iin46 then enters a slot 49 in the end of the f cxible shaft, a threaded sleeve 50 swiveled on a couplin ol'soldered on the end of the casing of t e flexible shaft being then screwed .onto'tihe threaded boss 44. Another odometer 52is permanently mounted in the curved top 7'of the magneto case, being carried by a transverse bar 53. This odometer has a star-wheel 54 which is engaged b a pin 55 projecting from a gear 56 whici is journaled on a stud 57, secured in one end of the case 6. When this case is slid into position uponthe'magneto, the gear 56 engages with the ear 40 onthe driving-shaft 41. The case of the milli-volt-meter 34 contains a variable resistance 56, interposed in the circuit between the m eto and the terminals 57 of the meter-winding, by which themeter may be accurately calibrated, so that the same speed-scale may be e plo oil in meters, notw thstanding sum 1 di er one in the electric current fed to them by diferent dynamos, or in the torque thereby produced in each instrument.

By the specified construction, I am enabled to successfully employ a direct-eurrent low-tension magneto and a m-illi-volt meter or milli-am neter to indicate the speed of an automobile, something which has heretofore been deemed impossible on account .of the dificult in commutating the very weak current eveloped, and the high commutatorspeed which would exist if the armature were carried by a shaft di rectly driven by the pinion engaging the gear on the automobile-wheel. The use of commutator-segments and brushes of inoxidizable irecious metals or alloysof different har ness enables me to provide a commutator of invariable resistance, the worn brushes of which may be readily renewed at small ex ense.

The item vehic e, as used in the claims, is intended to include land, water and aerial conve ances.

I c aim:

1. -In a tachometer consisting of a directcurrent magnetohaving-a commutator and an electric meter in circuit therewith, the combination with the magneto of a substantially waterand dust-proof case therefor, a shaft extending'throu h said case and adapted to be driven at high speed, a-nd reduction gears in said case between said shaft and the magneto commutator-shaft.

'2. Ian vehicle tachometer consisting of a direct-current magneto having acommuta- .tor and an electric meteryin circuit therewith, the' combination with the ma eto of a substantiallynvaterand dust-proo case therefor, a shaft extending through said case, a pinion on'the outer end of said shaft, a gear adapted to be carried by a vehicle wheel and mesh with saidpinion, and reduction gears in said case between said shaft and the magneto commutator-shaft;

3. In a vehicle tachometer consisting of a direct-current magneto and an electric meter in circuit therewith, the combination with the magneto of a substantially waterand dust-proof case therefor, a shaft extend ng through said case and having a pinion adapted to mesh with a gear on E'VGl'IIClL-B- wheel, and. ears in said case between said shaft and tie 'magneto commutator-shaft. having teeth of smaller pitch than those of said mien. f

'4. in a vehicle tachometer consisting of a direct-current magneto and an electric meter in circuit therewith, the combination with the magneto of a substantially waterand" dust-proof case therefor, consisting of a base-plate, end-plates integral therewith, and'a removable cover, the field-magnet of the magneto being screwed to said base and clamped to one end-plate, a shaft extending through said case andadapted to be driven by the vehicle, and gears in said case between said shaft and the armature-shaft.

5. In a vehicle tachometer consisting of a direct-current magneto having a commutator and brushes and an electric meter in cirdirect-current magneto and an electric meter in circuit therewith, the combination with the magneto of a substantially waterand dust-proof case therefor consisting of a baseplate, end-plates having marginal grooves, and a removable cover having recesses receiving said end-plates and mar inal flanges which enter said grooves, a sha t extendlng through said case and adapted to be driven by the vehicle, and gears in said case between said shaft and the armature-shaft.

7. In a vehicle tachometer consistin of a direct -cn'rrentmagneto and an e ectric meterin circuit therewith, the combination with the magneto of a substantially-waterand dust-proof case therefor consisting of a flanged base-plate, end-plates having marginal grooves, and a removable cover iav n recesses receiving said end-plates, margina flanges which enter said grooves, and lower edges which scat against the base-flanges, a shaft extending through said case and adapted to be driven by the vehicle, and gears in said case between said shaft and-the armature-shaft.

8. In a vehicle tachometer consisting of a direct-current magneto and an electric meter in circuit therewith, the combination with the magneto of a case therefor consistingof a base-plate, end-plates, and a removable cover, a driving shaft journaled in said end -plates, extending through said case, and adapted to be driven by the vehicle, gears in said case between said shaft and the armature-shaft, and an odometer gear carried by said cover and detachably geared to said driving-shaft.

9. In a vehicle tachometer consisting of a direct-current ma neto and an electric meter in circuit therewith, the combination with the magneto of a case therefor consisting of a base-plate, end-plates, and a removable cover, one end-plate having an opening, a pin reniovably secured in said opening, a shaft extending through said case and adapted to be driven by the vehicle, an armatureshaft journaled at one end in said plug and at the other end in the other end-plate, and gears in said case between the driving-shaft and the armature-shaft.

In testimon whereof, I aflix my signature in presence 0 two Witnesses.

NEVIL MONROE HOPKINS \Vitnesses:

EUGENE A. BYRNES, Jos. H. BLAGKFORD. 

